Short-flame method of burning pulverized fuel.



' J. G. COUTANT.. 7 SHORT FLAME METHOD OF BURNING PULVERIZED FUEL. I

. APRLICATION FILED MAR. I2, 1915. 1 1,149,734. Patented Aug. 10,1915.

TED srAr s JAY G. COU'I'ANT, OF CHICAGO. ILLINOIS, ASSIGNOR TO WILLIA M M. SIIVIPSQN, 01

I CHICAGO, ILLINOIS.

SHORT-FLAME METHOD OF BURNING PULVERIZED FUEL.

of pulverized solid fuel it is applicable with W good results to the burning of other forms of carbonaceous fuel. I

It is an object of my invention to provide a method of burning carbonaceous fuel whereby a clear short flame of great heating power may be produced, the smoke which is ordinarily incidental to short flame combustion being entirely eliminated,

A further object of my invention is the provision of a method of burning carbonaceous fuel in which the heat necessaryto bring the fuel to the ignition temperature is obtained from the combustion of a portion of the fuel rather than byradiation from the walls of the furnace.

Another object of my invention is the provisionof a method of burning pulverized solid fuel, whereby the fuel may be ignited directly by means of a torch, thus obviating the necessity of preheating the burner. and thereby materially increasing the efficiency of the burner.

A further object of my invention is to provide a method of burning pulverized solid fuel, whereby combustion is almost instantaneous and is practically completed at or near the junction of the combustion chamber of the burner with the furnace.

Other objects and advantages of my in vention will be apparent as it is better understood by reference to the following specification when read in connection with the accompanying drawing. in which Figurcl is an elevation partially in section of a furnace equipped with a burner according to my invention. together with a controller for supplying fuel thereto, and

Fig. 2 is an enlarged vertical section through the burner.

Heretofore two" methods of burning pulverized solid fuel have been known. The first is the long flame method and consists, briefly, in injecting pulverized fuel mixed Specification of Letters Patent,

Application tiled March 12. 1915. Serial No. 1 3,861

with a quantity of air at a high velocity into a furnace chamber. This method is adapt: ed only for use in long chambers; such as the cement kiln. The combustion takes place only upon the outside of the cloud of fuel and the result is an elongated cone flame. The second method is the so-called short flame method and it is to suchamethod that my invention relates. Heretofore short flame methods of burning pulverized solid fuel have been operated on the principle of mixing all of the-combustion air with the fuel, injecting it in a diffused state into the furnace chamber. This produces a lazv smoky flame of low heating value, which is totally unadapted for most purposes and hence has met with no success in the practical art.

lVith the constantly rising'price of fuel oil it is extremely desirable that some method be devised whereby pulverized solid Gil fuel, such asanthracite and bituminous coal, V

peat, etc., may be burned with a clear short flame, such as it is already possible to attain with oil burners. Practical use has demonstrated that the process which I am about to describe effects this long desired.

result.

Referring to the drawings. 1 designates a small forging furnace and is indicative merely of a large class of furnaces to which my invention is applicable and 2 designates generally the burner according to my invention, which is attached to one side of the furnace and is connected by means of a pipe 3 to a source of pulverized fuel, in this instance a controller d, described in my copending application, Serial No. 859,355. filed August 31, 1914. The pul erized fuel is drawn into the pipe 3 by means of an injector at 5, supplied with air under pressure from a pipe 6 and controlled by a valve 7. as described in my copending application above referredto. Air is supplied to the burner through a. pipe 8, connected to any suitable source of supply under pressure, and is controlled by a valve 9 in the pipe.

The burner comprises the walls 10, constructed of refractory material, such as brick. and is supported in any suitable manner adjacent one side of the furnace 1,, a metal bracket 11 being provided in this in stance to support the burner. lhe burner is provided with two distinct chambers 12 and 13, in this instance disposed normal to each other, which may be termed, respectively, the preheating and final combustion chambers, and a passage 14 of smaller cross-sectional area than the chamber 12, communicating with one end thereof and arranged substantially concentrically therewith. At the junction of the chamber 12 and the passage 14, the shoulder 15 is formed, the function of which will presently appear. It is to be understood that the chambers 12 and 13 and the passage 14 may be circular in section or of any other suitable form.

A nozzle 16 enters the end of the passage 14 remote from the shoulder 15 and is adapted to be connected to the pipe 3 to direct-a jet of fuel into the passage 14 and the chamber 12. A member 17 surrounds the nozzle 16, providing an air passage concentric therewith, whereby a jacket of air is directed into the passage 14 and the chamber 12 surrounding the jet of fuel. The member 17 provides a duct 18 leading'to the air supply pipe 8, the valve 9 being disposed at. the junction of the duct 18 and the pipe 8, and adapted to control the air supply. A duct 19 leads from the duct 18 to a point adjacent the junction of the chambers 12 and 13 and is adapted to' supply the final combustion air and to direct the resulting combustion prodnets in the desired direction. The jet of air issuing from the duct 19 also acts as an injector to draw the fuel from the chamber 12. In the form of the burner disclosed in the accompanying drawing the jet of final combustion air from the duct 19 has a di rection normal, to the direction of the fuel jet, but it is to be understood that this is merely illustrative and that it may be directed as desired. A lighting hole 20 is provided in the wall of the passage 14 adjacent the end of the nozzle 16 and a suitable plug 21 is normally disposed therein.

The method of operation is as follows: The pulverized solid fuel is drawn from the controller 4 into the pipe 3 by means of the injector 5 and is forced in the form of a fuel cloud, with the solid particles suspended in a limited quantity of air, into the-nozzle 16 and thence into the passage 14 and the chamber 12 in the form of a jet. The valve 7 may be set to deliver the desired quantity of fuel at the required velocity to the nozzle. It maybe noted that the best results are obtained when the fuel is finely pulverized so that approximately 95% would pass through a 200-mesh screen and when it is delivered at a velocity of approximately 4500 feet per minute. This insures the proper suspension of the fuel in the air and prevents clogging of the pipes and the nozzle. The valve 9 is then operated to admit air through the ducts 18 and 19to the burner and a torch is applied outside the lighting hole 20 and the flame is drawn into the chamber 12 to ignite the fuel in the preheating combustion chamber. Ignition will take place instantaneously, exactly as in the case of gas or 011,

it being unnecessary to preheat the burner,

by reason of the difference in velocities the air of the jacket surrounding the fuel jet draws particles of fuel away from the edges thereof and the arrangement of the chamber 12 is such that these particles Whirl away from the jet, as indicated in Fig. 2 of the drawing. owing to the tendency of the fuel and air jets to reduce the pressure near the walls of the chamber. This causes the particles of fuel to become thoroughly mixed with the air to form a combustible mixture, which burns when ignited and preheats the remainder of the fuel in the jet as it passes downwardly to the final combustion chamber 13. The fuel of the jet during its travel to the final combustion chamber 13 is preheated to the ignition point and at the lower end of the chamber 12 it meets the jet of air from the duct 19, ,which is sufiicient in quantity to complete the combustion of the fuel. Combustion is almost instantaneous, being practically complete at the entrance of the furnace and the incandesent combustion products pass into the furnace in the form of a clear, short and very hot flame.

It will be seen from the foregoing that I have devised a new and useful method involving a new principle of operation, whereby a short flame free from smoke may be produced. This method consists essentially in preheating a fuel jet by a surrounding zone of flame, the source of which is a part of the fuel jet itself. Bythe use of this method the fuel is no longer dependent upon radiation from the walls of the burner for the heat which is required to bring it to the ignition point and hence the operation is made more rapid and the results are more certain than has heretofore been possible. Other advantages of my method are the freedom of the flame from smoke and the ease with which the burner may be started.

It will be obvious that various changes may be made in the form, construction and arrangement of the parts Without departing from the spirit and scope of the invention or sacrificingv any of its material advantages, the form hereinbefore described being merely a preferred embodiment thereof.

I claim:

1. A short flame method of burning carbonaceous fuel, which comprises forming a jet of said fuel',-E--surrounding said jet with a jacket of combustion supporting gas, the gas of said jacket traveling in the same direction as said fuel jet and at a relatively higher velocity, whereby a portion of said fuel jet is caused to mix with the gas of said jacket, igniting said mixture to form and maintain a zone of flame, surrounding said fuel jet, to preheat the fuel particles to igniting temperature, and mixing the preheated fuel particles with sufficient combustion supporting gas to complete the combustion thereof.

2. A short flame method of burning carbonaceous fuel, which comprises forming a jet of said fuel, suspended in a gaseous medium, surrounding said jet With a jacket of combustion supporting gas, the gas of said jacket traveling in the same direction as said fuel jet'and at a relatively higher velocity, whereby a portion of said fuel jet is caused to mix with the gas of said jacket, igniting said mixture to form'and maintain a zone of flame, surrounding said fuel jet, to preheat the fuel particles to igniting temperature, and mixing the preheated fuel particles with sufficient combustion supporting gas to complete the combustion thereof.

3. A short flame method of burning car bonaceous fuel, which comprises forming a jet of said fuel, suspended in a gaseous medium, surrounding said jet with a jacket of combustion supporting gas, the gas of said jacket traveling in the same direction as said fuel jet and at a relatively higher velocity, whereby a portion of said fuel jet is caused to mix with the gas of said jacket, igniting said mixture to form and maintain a zone of flame, surrounding said fuel jet, to preheat the fuel particles to igniting temperature, and directing a jet of combustion supporting gas into the path of said preheated fuel particles 'to thoroughly mix said gas and particles and complete the combustion of said particles.

4. A short flame method of burning pulverized solid fuel, which comprises forming a jet of said fuel, suspended in a limited quantity of combustion supporting gas, surrounding said jet with a jacket of combustion supporting gas, the gas of said jacket traveling in the same direction as said fuel jet and at a relatively higher velocity, whereby a. portion of said fuel jet is caused to mix with the gas of said jacket, igniting said mixture to form and maintain a zone of flame, surrounding said fuel jet, to preheat the fuel particles to igniting temperature, and mixing the preheated fuel particles with sufficient combustion supporting gas to complete the combustion thereof.

5. A short flame method of burning pulverized solid fuel, which comprises forming a jet of said fuel, suspended in a limited quantity of air, surrounding said jet with a jacket of air, said air traveling in the same direction as said fuel jet and at a relatively higher velocity, whereby a portion of said fuel jet is caused to move outwardly to mix with the air of said jacket, igniting said mixture to form and maintain a zone of flame surrounding said fuel jet to preheat the fuel particles to igniting temperature, and mixing the preheated fuel particles with suflicient air to complete the combustion thereof:

6. A short flame method of burning pulverized solid fuel, which comprises directing a jet of said fuel, suspended in a limited quantity of combustion supporting gas, into a confined chamber, directing a jacket of combustion supporting gas into said chambei' surrounding said jet, the velocity of the gas of said jacket being relatively higher than the velocity of said jet, whereby parti cles of fuel from said jet are drawn outwardly into said jacket and the mixture is caused to whirl backwardly within the confines of said chamber, igniting said mixture to form and maintain a zone of flame, surrounding said fuel jet, to preheat the fuel particles, and directing a jet of combustion supporting gas into the path Ofsaid fuel jet, whereby a thorough mixture of said gas and preheated fuel is obtained and the resulting ignited combustion products are directed to the material to be treated.

7. A short flame method of burning pulverized solid fuel, which comprises directing a jet of said fuel, suspended in a limited quantity of air, into a confined chamber, directing a jacket of air into said chamber surroimding said jet, the velocity of the air of said jacket being relatively higher than the velocity of said jet, whereby particles of fuel from said jet are drawn outwardly into said jacket and the mixture is caused to whirl backwardly within the confines ofsaid chamber, igniting said mixture to form and maintain a zone of flame, surrounding said fuel jet, to preheat the fuel particles, and directing a jet of air at a velocity substantially equal to the velocity of the air of said jacket into the path of said fuel jet, whereby a thorough mixture of air and pre heated fuel is obtained and the resulting ignited combustion products are directed to the material to be treated.

8. A short flame method of burning pulverized solid fuel, which comprises directing a jet of said fuel suspended in a limited quantity of combustion supporting gas into a confined chamber, directing a jacket of combustion supporting gasinto said chamber, surrounding said jet, the velocity of gas of said jacket being relatively higher than the velocity of said jet, whereby particles of fuel from said jet are drawn outwardly into said jacket, the outside of said jacket being in contact with the walls of thoroughly mixed with said combustion supporting gas, and the resulting ignited com- 10 bustion products are directed to the material to be treated.

JAY G. (JOU'JX'XNI. Witnesses ERNEST H. MERCHANT, \V. T. W ESTERBERG. 

